The game is played with a cue
ball (the white ball) and fifteen object balls, numbered
1 through 15: 1-7 (solid colors), 9-15 (stripes) and 8-ball
(black).

One player must pocket balls
of solid colors, while the other player the striped ones.
The player pocketing his group first and then legally
pocketing the 8-ball wins the game.

Opening break

The balls are racked in a triangle with the 8-ball in the center of
the triangle, the first ball of the rack on the foot spot,
a stripe ball in one corner of the rack and a solid ball
in the other corner.

The game begins with the cue ball in hand behind the head string.

Any ball can be hit first by the cue ball

The break is legal when neither the cue ball nor the 8-ball is
pocketed, and either one of the numbered balls is
pocketed or four of them is driven to the rail.

In case of an illegal break, the oncoming player has the options

accepting the table in position

re-racking and breaking

re-racking and allowing the offending player to break again.

Pocketing the 8-ball on a legal break is not a foul. If the eight ball is pocketed, the
breaker has the option of

re-spotting the eight ball and accepting the balls in position

Re-breaking

If the breaker pockets the 8-ball and cue ball as well, the opponent has the option of

re-spotting the eight ball and shooting with cue ball in hand behind the head string

Re-breaking.

If the breaker pockets a ball and does not foul, he continues at the table, and the table
remains open.

Choice of group

Before groups are determined, the table is said to be “open”.

If the shooter legally pockets a ball while the table is open (except on the break shot), the corresponding
group becomes his, and his opponent is assigned the other group.

When the table is
open, any object ball may be struck first except the eight ball.

Continuing play

A player is entitled to continue shooting until he fails to legally pocket a ball of his group. It is no foul if he fails but then the opposing player is next.

A player has to complete one shot in 60 seconds, otherwise a foul is called, and incoming player gets cue ball in hand.

When all balls of a player's group are pocketed then the 8-ball has to be pocketed.

Fouls

The cue ball does not hit a ball of the player's group first, except when the table is open.

The cue ball is pocketed.

None of the balls is driven to the rail.

The shot is not completed in 60 seconds.

If a shot is foul the opposing player gets the cue ball in hand. This means that the player can place the cue ball anywhere on the table (does not have to be behind the head string).

Losing the game

It is a loss of frame for the shooter if

there is a foul when pocketing the eight ball

eight ball is pocketed before the shooter's group is cleared

These do not apply to the break shot.

Pro Mode

Pro rules can be activated in the "game and chat settings" of the game. (subscribers only)

Differences:

With pro rules shots has to be called (except the break shot). The system always offers a default ball and pocket, you only have to make a manual call if you wish to play another ball/pocket.

It is NOT a foul, if only non-called ball is pocketed, or a called ball is pocketed in a wrong pocket, but play passes to the opponent.

The shooter may call “safety” in which case play passes to the opponent at the end of the shot and any object ball pocketed on the safety remains pocketed.

It is a loss of frame foul to pocket the 8-ball in an uncalled pocket.